Radiofrequency Fields Preferentially Enhance In Vitro Cellular Radiosensitivity to Large Fractional Doses in a p53-Dependent Manner

Hypofractionated radiotherapy, which employs large fractions of ionizing radiation, is an effective treatment modality for most superficial cancers, but may result in severe side effects from normal tissue toxicity. It is, therefore, desirable to identify radiation modifying agents that potentiate the tumor inactivating effects of ionizing radiation and thereby lead to a reduction in radiation dose and prevent normal tissue toxicity. This study assessed the effect of radiofrequency fields (RFF), modulated at 100 and 1000 Hz, on the radiosensitivity of four human cell lines: MeWo (melanoma; p53 mutant), Be11 (melanoma; p53 wild-type), DU145 (prostate cancer; p53 mutant), and L132 (normal lung fibroblasts; p53 wild-type), using the colony assay. The magnetic flux densities that were induced in cell cultures ranged from 6.74 to 22.43 μT. The data demonstrate that RFF are more efficient in modulating large fractional doses of X-rays in a frequencyand cell-type-dependent manner. Their effects on radiosensitivity also appear to be linked to p53 status, with cells with mutant p53 being less sensitized than those that are p53 wildtype. These findings suggest that RFF could find application in hypofractionated radiotherapy as adjuvants, and can have a positive impact on the treatment of superficial tumors, and specifically tumors that are p53 wild-type.